The following U.S. Patents are incorporated herein by reference in entirety:
U.S. Pat. No. 5,820,426 discloses an exhaust system for a personal watercraft having an exhaust adapter plate and an exhaust header pipe that allows exhaust to exit from the rear of a horizontally-mounted internal combustion engine.
U.S. Pat. No. 9,534,526 discloses an elongated exhaust conduit comprising a first end receiving hot exhaust gas from a marine engine and a second end discharging the exhaust gas. An elongated cooling water jacket extends adjacent to the exhaust conduit. The cooling water jacket conveys the raw cooling water adjacent to the exhaust conduit to thereby cool the exhaust conduit and warm the raw cooling water therein and discharges the warmed cooling water to cool the marine engine. The cooling water jacket comprises first and second channels that are separate from each other. The cooling water is oriented in a helical flow around the exhaust conduit.
U.S. Pat. No. 9,616,987 discloses a marine engine including a cylinder block having first and second banks of cylinders that are disposed along a longitudinal axis and extend transversely with respect to each other in a V-shape so as to define a valley there between. A catalyst receptacle is disposed at least partially in the valley and contains at least one catalyst that treats exhaust gas from the marine engine. A conduit conveys the exhaust gas from the marine engine to the catalyst receptacle. The conduit receives the exhaust gas from the first and second banks of cylinders and conveys the exhaust gas to the catalyst receptacle. The conduit reverses direction only once with respect to the longitudinal axis.